a) Field of the Invention
The invention concerns a microphone comprising a diaphragm which has a first diaphragm surface which is preferably towards a sound source and on which sound waves impinge and a second diaphragm surface which is at least partially acoustically separated from the first diaphragm surface, and which preferably faces away from the sound source, at least one, preferably slot-shaped, sound inlet, through which sound waves can go to the second diaphragm surface and which forms substantially an acoustic inductance so that at least a part of the sound waves to be picked up is passed with a delay to the second diaphragm surface, and at least one damping element.
b) Description of the Related Art
U.S. Pat. No. 3,585,317 A discloses such a microphone, in which an acoustic resistance is formed by the slot-shaped sound inlet, in order to damp the sound which passes through the slot-shaped sound inlet. The directional effect of the microphone can be influenced by the sound inlet between the air volume behind the diaphragm and the outside air. So that the slot-shaped sound inlet has the required acoustic impedance its width is small in relation to length. To achieve acoustic inductance, the slot-shaped sound inlet is provided with inserts of hardenable wax.
DE 22 17 051 also discloses a microphone which has a slot-shaped sound inlet to form an acoustic resistance. In that case, the sound inlet is in the form of a groove-shaped recess in the magnet system which is made from sintered material. In such a microphone the directional effect of the microphone is heavily frequency-dependent and can be used mostly only for low frequencies. Production of the corresponding slot-shaped sound inlets in the magnet system of sintered material requires special tools, and tuning of the directional effect by varying the slot-shaped sound inlet can be implemented only by replacing the entire magnet system.